When mixing table-per-subclass with table-per-class-hierarchy, problem mapping inverse one-to-many relationship to derived entity

The attached test case can be used to reproduce. It includes two different inheritance mappings, one using standard TablePerSubclass without a discriminator, and one that uses a discriminator. The non-discriminator version works fine. The version with a discriminator generates an incorrect mapping (the AggregateRootId is created on both BaseEntity and DerivedEntity) and when lazy-loading the OneToMany collection, the join is against the AggregateRootId column on BaseEntity, which is null.

It seems to have something to do with the way the joined-subclass is mapped using a SingleTableSubclass when mixing inheritance strategies.

This is quite an important issue for us. I am willing to investigate further to try to come up with a proposed patch, however first wanted to confirm that my analysis was correct.